Contribution of infragravity waves to run-up and overwash in the pertuis breton embayment (France)

Contribution of infragravity waves to run-up and overwash in the pertuis breton embayment (France)

Lashley, Christopher H. (TU Delft Hydraulic Structures and Flood Risk)
Bertin, Xavier (Universite de la Rochelle-CNRS)
Roelvink, D. (IHE Delft Institute for Water Education)
Arnaud, Gaël (Universite de la Rochelle-CNRS; University of the French West Indies and Guiana)

2019

Wave run-up and dune overwash are typically assessed using empirical models developed for a specific range of often-simplistic conditions. Field experiments are essential in extending these formulae; yet obtaining comprehensive field data under extreme conditions is often challenging. Here, we use XBeach Surfbeat (XB-SB)-a shortwave-averaged but wave-group resolving numerical model-to complement a field campaign, with two main objectives: i) to assess the contribution of infragravity (IG) waves to washover development in a partially-sheltered area, with a highly complex bathymetry; and ii) to evaluate the unconventional nested-modeling approach that was applied. The analysis shows that gravity waves rapidly decrease across the embayment while IG waves are enhanced. Despite its exclusion of gravity-band swash, XB-SB is able to accurately reproduce both the large-scale hydrodynamics-wave heights and mean water levels across the 30 × 10 km embayment; and the local morphodynamics-steep post-storm dune profile and washover deposit. These findings show that the contribution of IG waves to dune overwash along the bay is significant and highlight the need for any method or model to consider IG waves when applied to similar environments. As many phase-averaged numerical models that are typically used for large-scale coastal applications exclude IG waves, XB-SB may prove to be a suitable alternative.

Coastal flooding
Combined field experiment and numerical modeling
Dune erosion
Infragravity waves
Overwash
Wave run-up
XBeach

http://resolver.tudelft.nl/uuid:1fb57923-224b-43ad-b33e-843b47abccc6

https://doi.org/10.3390/jmse7070205

2077-1312

Journal of Marine Science and Engineering, 7 (7)

Institutional Repository

journal article

© 2019 Christopher H. Lashley, Xavier Bertin, D. Roelvink, Gaël Arnaud